X-Git-Url: https://git.liburcu.org/?p=urcu.git;a=blobdiff_plain;f=rculfhash.c;h=638432a90b3121ef3c4b1a9d870680e1f6ba98f9;hp=6bc25aed32e09817bcf74280c19bc0022789551c;hb=91452a6aeb429d72aafaed0fd176cac5e742251d;hpb=df44348d52532adf7b7a28edc5fdf5b43255c36b diff --git a/rculfhash.c b/rculfhash.c index 6bc25ae..638432a 100644 --- a/rculfhash.c +++ b/rculfhash.c @@ -1,7 +1,7 @@ /* * rculfhash.c * - * Userspace RCU library - Lock-Free Expandable RCU Hash Table + * Userspace RCU library - Lock-Free Resizable RCU Hash Table * * Copyright 2010-2011 - Mathieu Desnoyers * @@ -29,7 +29,7 @@ * symposium on Parallel algorithms and architectures, ACM Press, * (2002), 73-82. * - * Some specificities of this Lock-Free Expandable RCU Hash Table + * Some specificities of this Lock-Free Resizable RCU Hash Table * implementation: * * - RCU read-side critical section allows readers to perform hash @@ -48,9 +48,13 @@ * - An index of dummy nodes is kept. These dummy nodes are the hash * table "buckets", and they are also chained together in the * split-ordered list, which allows recursive expansion. - * - The resize operation only allows expanding the hash table. - * It is triggered either through an API call or automatically by - * detecting long chains in the add operation. + * - The resize operation for small tables only allows expanding the hash table. + * It is triggered automatically by detecting long chains in the add + * operation. + * - The resize operation for larger tables (and available through an + * API) allows both expanding and shrinking the hash table. + * - Per-CPU Split-counters are used to keep track of the number of + * nodes within the hash table for automatic resize triggering. * - Resize operation initiated by long chain detection is executed by a * call_rcu thread, which keeps lock-freedom of add and remove. * - Resize operations are protected by a mutex. @@ -92,6 +96,39 @@ * - The per-order dummy node tables contain a compact version of the * hash table nodes. These tables are invariant after they are * populated into the hash table. + * + * A bit of ascii art explanation: + * + * Order index is the off-by-one compare to the actual power of 2 because + * we use index 0 to deal with the 0 special-case. + * + * This shows the nodes for a small table ordered by reversed bits: + * + * bits reverse + * 0 000 000 + * 4 100 001 + * 2 010 010 + * 6 110 011 + * 1 001 100 + * 5 101 101 + * 3 011 110 + * 7 111 111 + * + * This shows the nodes in order of non-reversed bits, linked by + * reversed-bit order. + * + * order bits reverse + * 0 0 000 000 + * | + * 1 | 1 001 100 <- <- + * | | | | + * 2 | | 2 010 010 | | + * | | | 3 011 110 | <- | + * | | | | | | | + * 3 -> | | | 4 100 001 | | + * -> | | 5 101 101 | + * -> | 6 110 011 + * -> 7 111 111 */ #define _LGPL_SOURCE @@ -107,7 +144,6 @@ #include #include #include -#include #include #include #include @@ -119,11 +155,36 @@ #define dbg_printf(fmt, args...) #endif -#define CHAIN_LEN_TARGET 4 -#define CHAIN_LEN_RESIZE_THRESHOLD 8 - -/* Commit counter changes to global counter each 1024 steps */ +/* + * Per-CPU split-counters lazily update the global counter each 1024 + * addition/removal. It automatically keeps track of resize required. + * We use the bucket length as indicator for need to expand for small + * tables and machines lacking per-cpu data suppport. + */ #define COUNT_COMMIT_ORDER 10 +#define CHAIN_LEN_TARGET 1 +#define CHAIN_LEN_RESIZE_THRESHOLD 3 + +/* + * Define the minimum table size. + */ +#define MIN_TABLE_SIZE 1 + +#if (CAA_BITS_PER_LONG == 32) +#define MAX_TABLE_ORDER 32 +#else +#define MAX_TABLE_ORDER 64 +#endif + +/* + * Minimum number of dummy nodes to touch per thread to parallelize grow/shrink. + */ +#define MIN_PARTITION_PER_THREAD_ORDER 12 +#define MIN_PARTITION_PER_THREAD (1UL << MIN_PARTITION_PER_THREAD_ORDER) + +#ifndef min +#define min(a, b) ((a) < (b) ? (a) : (b)) +#endif #ifndef max #define max(a, b) ((a) > (b) ? (a) : (b)) @@ -131,6 +192,8 @@ /* * The removed flag needs to be updated atomically with the pointer. + * It indicates that no node must attach to the node scheduled for + * removal, and that node garbage collection must be performed. * The dummy flag does not require to be updated atomically with the * pointer, but it is added as a pointer low bit flag to save space. */ @@ -138,28 +201,51 @@ #define DUMMY_FLAG (1UL << 1) #define FLAGS_MASK ((1UL << 2) - 1) +/* Value of the end pointer. Should not interact with flags. */ +#define END_VALUE NULL + struct ht_items_count { - unsigned long v; + unsigned long add, del; } __attribute__((aligned(CAA_CACHE_LINE_SIZE))); +struct rcu_level { + struct rcu_head head; + struct _cds_lfht_node nodes[0]; +}; + struct rcu_table { - unsigned long size; /* always a power of 2 */ + unsigned long size; /* always a power of 2, shared (RCU) */ unsigned long resize_target; int resize_initiated; - struct rcu_head head; - struct _cds_lfht_node *tbl[0]; + struct rcu_level *tbl[MAX_TABLE_ORDER]; }; struct cds_lfht { - struct rcu_table *t; /* shared */ + struct rcu_table t; cds_lfht_hash_fct hash_fct; cds_lfht_compare_fct compare_fct; unsigned long hash_seed; + int flags; + /* + * We need to put the work threads offline (QSBR) when taking this + * mutex, because we use synchronize_rcu within this mutex critical + * section, which waits on read-side critical sections, and could + * therefore cause grace-period deadlock if we hold off RCU G.P. + * completion. + */ pthread_mutex_t resize_mutex; /* resize mutex: add/del mutex */ unsigned int in_progress_resize, in_progress_destroy; void (*cds_lfht_call_rcu)(struct rcu_head *head, void (*func)(struct rcu_head *head)); - unsigned long count; /* global approximate item count */ + void (*cds_lfht_synchronize_rcu)(void); + void (*cds_lfht_rcu_read_lock)(void); + void (*cds_lfht_rcu_read_unlock)(void); + void (*cds_lfht_rcu_thread_offline)(void); + void (*cds_lfht_rcu_thread_online)(void); + void (*cds_lfht_rcu_register_thread)(void); + void (*cds_lfht_rcu_unregister_thread)(void); + pthread_attr_t *resize_attr; /* Resize threads attributes */ + long count; /* global approximate item count */ struct ht_items_count *percpu_count; /* per-cpu item count */ }; @@ -168,6 +254,26 @@ struct rcu_resize_work { struct cds_lfht *ht; }; +struct partition_resize_work { + struct rcu_head head; + struct cds_lfht *ht; + unsigned long i, start, len; + void (*fct)(struct cds_lfht *ht, unsigned long i, + unsigned long start, unsigned long len); +}; + +enum add_mode { + ADD_DEFAULT = 0, + ADD_UNIQUE = 1, + ADD_REPLACE = 2, +}; + +static +struct cds_lfht_node *_cds_lfht_add(struct cds_lfht *ht, + unsigned long size, + struct cds_lfht_node *node, + enum add_mode mode, int dummy); + /* * Algorithm to reverse bits in a word by lookup table, extended to * 64-bit words. @@ -360,8 +466,18 @@ int get_count_order_ulong(unsigned long x) return order; } +#ifdef POISON_FREE +#define poison_free(ptr) \ + do { \ + memset(ptr, 0x42, sizeof(*(ptr))); \ + free(ptr); \ + } while (0) +#else +#define poison_free(ptr) free(ptr) +#endif + static -void cds_lfht_resize_lazy(struct cds_lfht *ht, struct rcu_table *t, int growth); +void cds_lfht_resize_lazy(struct cds_lfht *ht, unsigned long size, int growth); /* * If the sched_getcpu() and sysconf(_SC_NPROCESSORS_CONF) calls are @@ -369,9 +485,12 @@ void cds_lfht_resize_lazy(struct cds_lfht *ht, struct rcu_table *t, int growth); * In the unfortunate event the number of CPUs reported would be * inaccurate, we use modulo arithmetic on the number of CPUs we got. */ - #if defined(HAVE_SCHED_GETCPU) && defined(HAVE_SYSCONF) +static +void cds_lfht_resize_lazy_count(struct cds_lfht *ht, unsigned long size, + unsigned long count); + static long nr_cpus_mask = -1; static @@ -407,7 +526,7 @@ struct ht_items_count *alloc_per_cpu_items_count(void) static void free_per_cpu_items_count(struct ht_items_count *count) { - free(count); + poison_free(count); } static @@ -424,61 +543,72 @@ int ht_get_cpu(void) } static -unsigned long ht_count_update(struct cds_lfht *ht, unsigned int value) +void ht_count_add(struct cds_lfht *ht, unsigned long size) { + unsigned long percpu_count; int cpu; if (unlikely(!ht->percpu_count)) - return 0; + return; cpu = ht_get_cpu(); if (unlikely(cpu < 0)) - return 0; - return uatomic_add_return(&ht->percpu_count[cpu].v, 1); -} - -static -void ht_count_add(struct cds_lfht *ht, struct rcu_table *t) -{ - unsigned long percpu_count; - - percpu_count = ht_count_update(ht, 1); + return; + percpu_count = uatomic_add_return(&ht->percpu_count[cpu].add, 1); if (unlikely(!(percpu_count & ((1UL << COUNT_COMMIT_ORDER) - 1)))) { - unsigned long count; + long count; dbg_printf("add percpu %lu\n", percpu_count); count = uatomic_add_return(&ht->count, 1UL << COUNT_COMMIT_ORDER); /* If power of 2 */ if (!(count & (count - 1))) { - dbg_printf("add global %lu\n", count); - cds_lfht_resize_lazy(ht, t, 1); + if ((count >> CHAIN_LEN_RESIZE_THRESHOLD) < size) + return; + dbg_printf("add set global %ld\n", count); + cds_lfht_resize_lazy_count(ht, size, + count >> (CHAIN_LEN_TARGET - 1)); } } } static -void ht_count_remove(struct cds_lfht *ht, struct rcu_table *t) +void ht_count_del(struct cds_lfht *ht, unsigned long size) { unsigned long percpu_count; + int cpu; - percpu_count = ht_count_update(ht, -1); + if (unlikely(!ht->percpu_count)) + return; + cpu = ht_get_cpu(); + if (unlikely(cpu < 0)) + return; + percpu_count = uatomic_add_return(&ht->percpu_count[cpu].del, 1); if (unlikely(!(percpu_count & ((1UL << COUNT_COMMIT_ORDER) - 1)))) { - unsigned long count; + long count; - dbg_printf("remove percpu %lu\n", percpu_count); + dbg_printf("del percpu %lu\n", percpu_count); count = uatomic_add_return(&ht->count, - 1UL << COUNT_COMMIT_ORDER); + -(1UL << COUNT_COMMIT_ORDER)); /* If power of 2 */ if (!(count & (count - 1))) { - dbg_printf("remove global %lu\n", count); - cds_lfht_resize_lazy(ht, t, -1); + if ((count >> CHAIN_LEN_RESIZE_THRESHOLD) >= size) + return; + dbg_printf("del set global %ld\n", count); + /* + * Don't shrink table if the number of nodes is below a + * certain threshold. + */ + if (count < (1UL << COUNT_COMMIT_ORDER) * (nr_cpus_mask + 1)) + return; + cds_lfht_resize_lazy_count(ht, size, + count >> (CHAIN_LEN_TARGET - 1)); } } } #else /* #if defined(HAVE_SCHED_GETCPU) && defined(HAVE_SYSCONF) */ -static const long nr_cpus_mask = -1; +static const long nr_cpus_mask = -2; static struct ht_items_count *alloc_per_cpu_items_count(void) @@ -492,12 +622,12 @@ void free_per_cpu_items_count(struct ht_items_count *count) } static -void ht_count_add(struct cds_lfht *ht) +void ht_count_add(struct cds_lfht *ht, unsigned long size) { } static -void ht_count_remove(struct cds_lfht *ht) +void ht_count_del(struct cds_lfht *ht, unsigned long size) { } @@ -505,15 +635,24 @@ void ht_count_remove(struct cds_lfht *ht) static -void check_resize(struct cds_lfht *ht, struct rcu_table *t, - uint32_t chain_len) +void check_resize(struct cds_lfht *ht, unsigned long size, uint32_t chain_len) { - return; //TEST + unsigned long count; + + if (!(ht->flags & CDS_LFHT_AUTO_RESIZE)) + return; + count = uatomic_read(&ht->count); + /* + * Use bucket-local length for small table expand and for + * environments lacking per-cpu data support. + */ + if (count >= (1UL << COUNT_COMMIT_ORDER)) + return; if (chain_len > 100) dbg_printf("WARNING: large chain length: %u.\n", chain_len); if (chain_len >= CHAIN_LEN_RESIZE_THRESHOLD) - cds_lfht_resize_lazy(ht, t, + cds_lfht_resize_lazy(ht, size, get_count_order_u32(chain_len - (CHAIN_LEN_TARGET - 1))); } @@ -546,7 +685,19 @@ struct cds_lfht_node *flag_dummy(struct cds_lfht_node *node) { return (struct cds_lfht_node *) (((unsigned long) node) | DUMMY_FLAG); } - + +static +struct cds_lfht_node *get_end(void) +{ + return (struct cds_lfht_node *) END_VALUE; +} + +static +int is_end(struct cds_lfht_node *node) +{ + return clear_flag(node) == (struct cds_lfht_node *) END_VALUE; +} + static unsigned long _uatomic_max(unsigned long *ptr, unsigned long v) { @@ -561,6 +712,14 @@ unsigned long _uatomic_max(unsigned long *ptr, unsigned long v) return v; } +static +void cds_lfht_free_level(struct rcu_head *head) +{ + struct rcu_level *l = + caa_container_of(head, struct rcu_level, head); + poison_free(l); +} + /* * Remove all logically deleted nodes from a bucket up to a certain node key. */ @@ -569,13 +728,24 @@ void _cds_lfht_gc_bucket(struct cds_lfht_node *dummy, struct cds_lfht_node *node { struct cds_lfht_node *iter_prev, *iter, *next, *new_next; + assert(!is_dummy(dummy)); + assert(!is_removed(dummy)); + assert(!is_dummy(node)); + assert(!is_removed(node)); for (;;) { iter_prev = dummy; /* We can always skip the dummy node initially */ iter = rcu_dereference(iter_prev->p.next); assert(iter_prev->p.reverse_hash <= node->p.reverse_hash); + /* + * We should never be called with dummy (start of chain) + * and logically removed node (end of path compression + * marker) being the actual same node. This would be a + * bug in the algorithm implementation. + */ + assert(dummy != node); for (;;) { - if (unlikely(!clear_flag(iter))) + if (unlikely(is_end(iter))) return; if (likely(clear_flag(iter)->p.reverse_hash > node->p.reverse_hash)) return; @@ -590,22 +760,103 @@ void _cds_lfht_gc_bucket(struct cds_lfht_node *dummy, struct cds_lfht_node *node new_next = flag_dummy(clear_flag(next)); else new_next = clear_flag(next); + if (is_removed(iter)) + new_next = flag_removed(new_next); (void) uatomic_cmpxchg(&iter_prev->p.next, iter, new_next); } + return; } static -struct cds_lfht_node *_cds_lfht_add(struct cds_lfht *ht, struct rcu_table *t, - struct cds_lfht_node *node, int unique, int dummy) +int _cds_lfht_replace(struct cds_lfht *ht, unsigned long size, + struct cds_lfht_node *old_node, + struct cds_lfht_node *ret_next, + struct cds_lfht_node *new_node) +{ + struct cds_lfht_node *dummy, *old_next; + struct _cds_lfht_node *lookup; + int flagged = 0; + unsigned long hash, index, order; + + if (!old_node) /* Return -ENOENT if asked to replace NULL node */ + goto end; + + assert(!is_removed(old_node)); + assert(!is_dummy(old_node)); + assert(!is_removed(new_node)); + assert(!is_dummy(new_node)); + assert(new_node != old_node); + do { + /* Insert after node to be replaced */ + old_next = ret_next; + if (is_removed(old_next)) { + /* + * Too late, the old node has been removed under us + * between lookup and replace. Fail. + */ + goto end; + } + assert(!is_dummy(old_next)); + assert(new_node != clear_flag(old_next)); + new_node->p.next = clear_flag(old_next); + /* + * Here is the whole trick for lock-free replace: we add + * the replacement node _after_ the node we want to + * replace by atomically setting its next pointer at the + * same time we set its removal flag. Given that + * the lookups/get next use an iterator aware of the + * next pointer, they will either skip the old node due + * to the removal flag and see the new node, or use + * the old node, but will not see the new one. + */ + ret_next = uatomic_cmpxchg(&old_node->p.next, + old_next, flag_removed(new_node)); + } while (ret_next != old_next); + + /* We performed the replacement. */ + flagged = 1; + + /* + * Ensure that the old node is not visible to readers anymore: + * lookup for the node, and remove it (along with any other + * logically removed node) if found. + */ + hash = bit_reverse_ulong(old_node->p.reverse_hash); + assert(size > 0); + index = hash & (size - 1); + order = get_count_order_ulong(index + 1); + lookup = &ht->t.tbl[order]->nodes[index & (!order ? 0 : ((1UL << (order - 1)) - 1))]; + dummy = (struct cds_lfht_node *) lookup; + _cds_lfht_gc_bucket(dummy, new_node); +end: + /* + * Only the flagging action indicated that we (and no other) + * replaced the node from the hash table. + */ + if (flagged) { + assert(is_removed(rcu_dereference(old_node->p.next))); + return 0; + } else { + return -ENOENT; + } +} + +static +struct cds_lfht_node *_cds_lfht_add(struct cds_lfht *ht, + unsigned long size, + struct cds_lfht_node *node, + enum add_mode mode, int dummy) { struct cds_lfht_node *iter_prev, *iter, *next, *new_node, *new_next, - *dummy_node; + *dummy_node, *return_node; struct _cds_lfht_node *lookup; unsigned long hash, index, order; - if (!t->size) { + assert(!is_dummy(node)); + assert(!is_removed(node)); + if (!size) { assert(dummy); - node->p.next = flag_dummy(NULL); + node->p.next = flag_dummy(get_end()); return node; /* Initial first add (head) */ } hash = bit_reverse_ulong(node->p.reverse_hash); @@ -616,37 +867,43 @@ struct cds_lfht_node *_cds_lfht_add(struct cds_lfht *ht, struct rcu_table *t, * iter_prev points to the non-removed node prior to the * insert location. */ - index = hash & (t->size - 1); + index = hash & (size - 1); order = get_count_order_ulong(index + 1); - lookup = &t->tbl[order][index & ((1UL << (order - 1)) - 1)]; + lookup = &ht->t.tbl[order]->nodes[index & ((!order ? 0 : (1UL << (order - 1))) - 1)]; iter_prev = (struct cds_lfht_node *) lookup; /* We can always skip the dummy node initially */ iter = rcu_dereference(iter_prev->p.next); assert(iter_prev->p.reverse_hash <= node->p.reverse_hash); for (;;) { - if (unlikely(!clear_flag(iter))) + if (unlikely(is_end(iter))) goto insert; if (likely(clear_flag(iter)->p.reverse_hash > node->p.reverse_hash)) goto insert; next = rcu_dereference(clear_flag(iter)->p.next); if (unlikely(is_removed(next))) goto gc_node; - if (unique + if ((mode == ADD_UNIQUE || mode == ADD_REPLACE) && !is_dummy(next) && !ht->compare_fct(node->key, node->key_len, clear_flag(iter)->key, - clear_flag(iter)->key_len)) - return clear_flag(iter); + clear_flag(iter)->key_len)) { + if (mode == ADD_UNIQUE) + return clear_flag(iter); + else /* mode == ADD_REPLACE */ + goto replace; + } /* Only account for identical reverse hash once */ if (iter_prev->p.reverse_hash != clear_flag(iter)->p.reverse_hash && !is_dummy(next)) - check_resize(ht, t, ++chain_len); + check_resize(ht, size, ++chain_len); iter_prev = clear_flag(iter); iter = next; } + insert: assert(node != clear_flag(iter)); assert(!is_removed(iter_prev)); + assert(!is_removed(iter)); assert(iter_prev != node); if (!dummy) node->p.next = clear_flag(iter); @@ -657,10 +914,26 @@ struct cds_lfht_node *_cds_lfht_add(struct cds_lfht *ht, struct rcu_table *t, else new_node = node; if (uatomic_cmpxchg(&iter_prev->p.next, iter, - new_node) != iter) + new_node) != iter) { continue; /* retry */ - else + } else { + if (mode == ADD_REPLACE) + return_node = NULL; + else /* ADD_DEFAULT and ADD_UNIQUE */ + return_node = node; goto gc_end; + } + + replace: + + if (!_cds_lfht_replace(ht, size, clear_flag(iter), next, + node)) { + return_node = clear_flag(iter); + goto end; /* gc already done */ + } else { + continue; /* retry */ + } + gc_node: assert(!is_removed(iter)); if (is_dummy(iter)) @@ -672,32 +945,44 @@ struct cds_lfht_node *_cds_lfht_add(struct cds_lfht *ht, struct rcu_table *t, } gc_end: /* Garbage collect logically removed nodes in the bucket */ - index = hash & (t->size - 1); + index = hash & (size - 1); order = get_count_order_ulong(index + 1); - lookup = &t->tbl[order][index & ((1UL << (order - 1)) - 1)]; + lookup = &ht->t.tbl[order]->nodes[index & (!order ? 0 : ((1UL << (order - 1)) - 1))]; dummy_node = (struct cds_lfht_node *) lookup; _cds_lfht_gc_bucket(dummy_node, node); - return node; +end: + return return_node; } static -int _cds_lfht_remove(struct cds_lfht *ht, struct rcu_table *t, - struct cds_lfht_node *node) +int _cds_lfht_del(struct cds_lfht *ht, unsigned long size, + struct cds_lfht_node *node, + int dummy_removal) { struct cds_lfht_node *dummy, *next, *old; struct _cds_lfht_node *lookup; int flagged = 0; unsigned long hash, index, order; + if (!node) /* Return -ENOENT if asked to delete NULL node */ + goto end; + /* logically delete the node */ + assert(!is_dummy(node)); + assert(!is_removed(node)); old = rcu_dereference(node->p.next); do { + struct cds_lfht_node *new_next; + next = old; if (unlikely(is_removed(next))) goto end; - assert(!is_dummy(next)); - old = uatomic_cmpxchg(&node->p.next, next, - flag_removed(next)); + if (dummy_removal) + assert(is_dummy(next)); + else + assert(!is_dummy(next)); + new_next = flag_removed(next); + old = uatomic_cmpxchg(&node->p.next, next, new_next); } while (old != next); /* We performed the (logical) deletion. */ @@ -709,9 +994,10 @@ int _cds_lfht_remove(struct cds_lfht *ht, struct rcu_table *t, * if found. */ hash = bit_reverse_ulong(node->p.reverse_hash); - index = hash & (t->size - 1); + assert(size > 0); + index = hash & (size - 1); order = get_count_order_ulong(index + 1); - lookup = &t->tbl[order][index & ((1UL << (order - 1)) - 1)]; + lookup = &ht->t.tbl[order]->nodes[index & (!order ? 0 : ((1UL << (order - 1)) - 1))]; dummy = (struct cds_lfht_node *) lookup; _cds_lfht_gc_bucket(dummy, node); end: @@ -722,12 +1008,117 @@ end: if (flagged) { assert(is_removed(rcu_dereference(node->p.next))); return 0; - } else + } else { return -ENOENT; + } } static -void init_table(struct cds_lfht *ht, struct rcu_table *t, +void *partition_resize_thread(void *arg) +{ + struct partition_resize_work *work = arg; + + work->ht->cds_lfht_rcu_register_thread(); + work->fct(work->ht, work->i, work->start, work->len); + work->ht->cds_lfht_rcu_unregister_thread(); + return NULL; +} + +static +void partition_resize_helper(struct cds_lfht *ht, unsigned long i, + unsigned long len, + void (*fct)(struct cds_lfht *ht, unsigned long i, + unsigned long start, unsigned long len)) +{ + unsigned long partition_len; + struct partition_resize_work *work; + int thread, ret; + unsigned long nr_threads; + pthread_t *thread_id; + + /* + * Note: nr_cpus_mask + 1 is always power of 2. + * We spawn just the number of threads we need to satisfy the minimum + * partition size, up to the number of CPUs in the system. + */ + if (nr_cpus_mask > 0) { + nr_threads = min(nr_cpus_mask + 1, + len >> MIN_PARTITION_PER_THREAD_ORDER); + } else { + nr_threads = 1; + } + partition_len = len >> get_count_order_ulong(nr_threads); + work = calloc(nr_threads, sizeof(*work)); + thread_id = calloc(nr_threads, sizeof(*thread_id)); + assert(work); + for (thread = 0; thread < nr_threads; thread++) { + work[thread].ht = ht; + work[thread].i = i; + work[thread].len = partition_len; + work[thread].start = thread * partition_len; + work[thread].fct = fct; + ret = pthread_create(&thread_id[thread], ht->resize_attr, + partition_resize_thread, &work[thread]); + assert(!ret); + } + for (thread = 0; thread < nr_threads; thread++) { + ret = pthread_join(thread_id[thread], NULL); + assert(!ret); + } + free(work); + free(thread_id); +} + +/* + * Holding RCU read lock to protect _cds_lfht_add against memory + * reclaim that could be performed by other call_rcu worker threads (ABA + * problem). + * + * When we reach a certain length, we can split this population phase over + * many worker threads, based on the number of CPUs available in the system. + * This should therefore take care of not having the expand lagging behind too + * many concurrent insertion threads by using the scheduler's ability to + * schedule dummy node population fairly with insertions. + */ +static +void init_table_populate_partition(struct cds_lfht *ht, unsigned long i, + unsigned long start, unsigned long len) +{ + unsigned long j; + + ht->cds_lfht_rcu_read_lock(); + for (j = start; j < start + len; j++) { + struct cds_lfht_node *new_node = + (struct cds_lfht_node *) &ht->t.tbl[i]->nodes[j]; + + dbg_printf("init populate: i %lu j %lu hash %lu\n", + i, j, !i ? 0 : (1UL << (i - 1)) + j); + new_node->p.reverse_hash = + bit_reverse_ulong(!i ? 0 : (1UL << (i - 1)) + j); + (void) _cds_lfht_add(ht, !i ? 0 : (1UL << (i - 1)), + new_node, ADD_DEFAULT, 1); + if (CMM_LOAD_SHARED(ht->in_progress_destroy)) + break; + } + ht->cds_lfht_rcu_read_unlock(); +} + +static +void init_table_populate(struct cds_lfht *ht, unsigned long i, + unsigned long len) +{ + assert(nr_cpus_mask != -1); + if (nr_cpus_mask < 0 || len < 2 * MIN_PARTITION_PER_THREAD) { + ht->cds_lfht_rcu_thread_online(); + init_table_populate_partition(ht, i, 0, len); + ht->cds_lfht_rcu_thread_offline(); + return; + } + partition_resize_helper(ht, i, len, init_table_populate_partition); +} + +static +void init_table(struct cds_lfht *ht, unsigned long first_order, unsigned long len_order) { unsigned long i, end_order; @@ -735,40 +1126,162 @@ void init_table(struct cds_lfht *ht, struct rcu_table *t, dbg_printf("init table: first_order %lu end_order %lu\n", first_order, first_order + len_order); end_order = first_order + len_order; - t->size = !first_order ? 0 : (1UL << (first_order - 1)); for (i = first_order; i < end_order; i++) { - unsigned long j, len; + unsigned long len; len = !i ? 1 : 1UL << (i - 1); dbg_printf("init order %lu len: %lu\n", i, len); - t->tbl[i] = calloc(len, sizeof(struct _cds_lfht_node)); - for (j = 0; j < len; j++) { - dbg_printf("init entry: i %lu j %lu hash %lu\n", - i, j, !i ? 0 : (1UL << (i - 1)) + j); - struct cds_lfht_node *new_node = - (struct cds_lfht_node *) &t->tbl[i][j]; - new_node->p.reverse_hash = - bit_reverse_ulong(!i ? 0 : (1UL << (i - 1)) + j); - (void) _cds_lfht_add(ht, t, new_node, 0, 1); - if (CMM_LOAD_SHARED(ht->in_progress_destroy)) - break; - } - /* Update table size */ - t->size = !i ? 1 : (1UL << i); - dbg_printf("init new size: %lu\n", t->size); + + /* Stop expand if the resize target changes under us */ + if (CMM_LOAD_SHARED(ht->t.resize_target) < (!i ? 1 : (1UL << i))) + break; + + ht->t.tbl[i] = calloc(1, sizeof(struct rcu_level) + + (len * sizeof(struct _cds_lfht_node))); + assert(ht->t.tbl[i]); + + /* + * Set all dummy nodes reverse hash values for a level and + * link all dummy nodes into the table. + */ + init_table_populate(ht, i, len); + + /* + * Update table size. + */ + cmm_smp_wmb(); /* populate data before RCU size */ + CMM_STORE_SHARED(ht->t.size, !i ? 1 : (1UL << i)); + + dbg_printf("init new size: %lu\n", !i ? 1 : (1UL << i)); if (CMM_LOAD_SHARED(ht->in_progress_destroy)) break; } - t->resize_target = t->size; - t->resize_initiated = 0; } -struct cds_lfht *cds_lfht_new(cds_lfht_hash_fct hash_fct, +/* + * Holding RCU read lock to protect _cds_lfht_remove against memory + * reclaim that could be performed by other call_rcu worker threads (ABA + * problem). + * For a single level, we logically remove and garbage collect each node. + * + * As a design choice, we perform logical removal and garbage collection on a + * node-per-node basis to simplify this algorithm. We also assume keeping good + * cache locality of the operation would overweight possible performance gain + * that could be achieved by batching garbage collection for multiple levels. + * However, this would have to be justified by benchmarks. + * + * Concurrent removal and add operations are helping us perform garbage + * collection of logically removed nodes. We guarantee that all logically + * removed nodes have been garbage-collected (unlinked) before call_rcu is + * invoked to free a hole level of dummy nodes (after a grace period). + * + * Logical removal and garbage collection can therefore be done in batch or on a + * node-per-node basis, as long as the guarantee above holds. + * + * When we reach a certain length, we can split this removal over many worker + * threads, based on the number of CPUs available in the system. This should + * take care of not letting resize process lag behind too many concurrent + * updater threads actively inserting into the hash table. + */ +static +void remove_table_partition(struct cds_lfht *ht, unsigned long i, + unsigned long start, unsigned long len) +{ + unsigned long j; + + ht->cds_lfht_rcu_read_lock(); + for (j = start; j < start + len; j++) { + struct cds_lfht_node *fini_node = + (struct cds_lfht_node *) &ht->t.tbl[i]->nodes[j]; + + dbg_printf("remove entry: i %lu j %lu hash %lu\n", + i, j, !i ? 0 : (1UL << (i - 1)) + j); + fini_node->p.reverse_hash = + bit_reverse_ulong(!i ? 0 : (1UL << (i - 1)) + j); + (void) _cds_lfht_del(ht, !i ? 0 : (1UL << (i - 1)), + fini_node, 1); + if (CMM_LOAD_SHARED(ht->in_progress_destroy)) + break; + } + ht->cds_lfht_rcu_read_unlock(); +} + +static +void remove_table(struct cds_lfht *ht, unsigned long i, unsigned long len) +{ + + assert(nr_cpus_mask != -1); + if (nr_cpus_mask < 0 || len < 2 * MIN_PARTITION_PER_THREAD) { + ht->cds_lfht_rcu_thread_online(); + remove_table_partition(ht, i, 0, len); + ht->cds_lfht_rcu_thread_offline(); + return; + } + partition_resize_helper(ht, i, len, remove_table_partition); +} + +static +void fini_table(struct cds_lfht *ht, + unsigned long first_order, unsigned long len_order) +{ + long i, end_order; + + dbg_printf("fini table: first_order %lu end_order %lu\n", + first_order, first_order + len_order); + end_order = first_order + len_order; + assert(first_order > 0); + for (i = end_order - 1; i >= first_order; i--) { + unsigned long len; + + len = !i ? 1 : 1UL << (i - 1); + dbg_printf("fini order %lu len: %lu\n", i, len); + + /* Stop shrink if the resize target changes under us */ + if (CMM_LOAD_SHARED(ht->t.resize_target) > (1UL << (i - 1))) + break; + + cmm_smp_wmb(); /* populate data before RCU size */ + CMM_STORE_SHARED(ht->t.size, 1UL << (i - 1)); + + /* + * We need to wait for all add operations to reach Q.S. (and + * thus use the new table for lookups) before we can start + * releasing the old dummy nodes. Otherwise their lookup will + * return a logically removed node as insert position. + */ + ht->cds_lfht_synchronize_rcu(); + + /* + * Set "removed" flag in dummy nodes about to be removed. + * Unlink all now-logically-removed dummy node pointers. + * Concurrent add/remove operation are helping us doing + * the gc. + */ + remove_table(ht, i, len); + + ht->cds_lfht_call_rcu(&ht->t.tbl[i]->head, cds_lfht_free_level); + + dbg_printf("fini new size: %lu\n", 1UL << i); + if (CMM_LOAD_SHARED(ht->in_progress_destroy)) + break; + } +} + +struct cds_lfht *_cds_lfht_new(cds_lfht_hash_fct hash_fct, cds_lfht_compare_fct compare_fct, unsigned long hash_seed, unsigned long init_size, + int flags, void (*cds_lfht_call_rcu)(struct rcu_head *head, - void (*func)(struct rcu_head *head))) + void (*func)(struct rcu_head *head)), + void (*cds_lfht_synchronize_rcu)(void), + void (*cds_lfht_rcu_read_lock)(void), + void (*cds_lfht_rcu_read_unlock)(void), + void (*cds_lfht_rcu_thread_offline)(void), + void (*cds_lfht_rcu_thread_online)(void), + void (*cds_lfht_rcu_register_thread)(void), + void (*cds_lfht_rcu_unregister_thread)(void), + pthread_attr_t *attr) { struct cds_lfht *ht; unsigned long order; @@ -777,46 +1290,60 @@ struct cds_lfht *cds_lfht_new(cds_lfht_hash_fct hash_fct, if (init_size && (init_size & (init_size - 1))) return NULL; ht = calloc(1, sizeof(struct cds_lfht)); + assert(ht); ht->hash_fct = hash_fct; ht->compare_fct = compare_fct; ht->hash_seed = hash_seed; ht->cds_lfht_call_rcu = cds_lfht_call_rcu; - ht->in_progress_resize = 0; + ht->cds_lfht_synchronize_rcu = cds_lfht_synchronize_rcu; + ht->cds_lfht_rcu_read_lock = cds_lfht_rcu_read_lock; + ht->cds_lfht_rcu_read_unlock = cds_lfht_rcu_read_unlock; + ht->cds_lfht_rcu_thread_offline = cds_lfht_rcu_thread_offline; + ht->cds_lfht_rcu_thread_online = cds_lfht_rcu_thread_online; + ht->cds_lfht_rcu_register_thread = cds_lfht_rcu_register_thread; + ht->cds_lfht_rcu_unregister_thread = cds_lfht_rcu_unregister_thread; + ht->resize_attr = attr; ht->percpu_count = alloc_per_cpu_items_count(); /* this mutex should not nest in read-side C.S. */ pthread_mutex_init(&ht->resize_mutex, NULL); - order = get_count_order_ulong(max(init_size, 1)) + 1; - ht->t = calloc(1, sizeof(struct cds_lfht) - + (order * sizeof(struct _cds_lfht_node *))); - ht->t->size = 0; + order = get_count_order_ulong(max(init_size, MIN_TABLE_SIZE)) + 1; + ht->flags = flags; + ht->cds_lfht_rcu_thread_offline(); pthread_mutex_lock(&ht->resize_mutex); - init_table(ht, ht->t, 0, order); + ht->t.resize_target = 1UL << (order - 1); + init_table(ht, 0, order); pthread_mutex_unlock(&ht->resize_mutex); + ht->cds_lfht_rcu_thread_online(); return ht; } -struct cds_lfht_node *cds_lfht_lookup(struct cds_lfht *ht, void *key, size_t key_len) +void cds_lfht_lookup(struct cds_lfht *ht, void *key, size_t key_len, + struct cds_lfht_iter *iter) { - struct rcu_table *t; - struct cds_lfht_node *node, *next; + struct cds_lfht_node *node, *next, *dummy_node; struct _cds_lfht_node *lookup; - unsigned long hash, reverse_hash, index, order; + unsigned long hash, reverse_hash, index, order, size; hash = ht->hash_fct(key, key_len, ht->hash_seed); reverse_hash = bit_reverse_ulong(hash); - t = rcu_dereference(ht->t); - index = hash & (t->size - 1); + size = rcu_dereference(ht->t.size); + index = hash & (size - 1); order = get_count_order_ulong(index + 1); - lookup = &t->tbl[order][index & ((1UL << (order - 1)) - 1)]; + lookup = &ht->t.tbl[order]->nodes[index & (!order ? 0 : ((1UL << (order - 1))) - 1)]; dbg_printf("lookup hash %lu index %lu order %lu aridx %lu\n", - hash, index, order, index & ((1UL << (order - 1)) - 1)); - node = (struct cds_lfht_node *) lookup; + hash, index, order, index & (!order ? 0 : ((1UL << (order - 1)) - 1))); + dummy_node = (struct cds_lfht_node *) lookup; + /* We can always skip the dummy node initially */ + node = rcu_dereference(dummy_node->p.next); + node = clear_flag(node); for (;;) { - if (unlikely(!node)) + if (unlikely(is_end(node))) { + node = next = NULL; break; + } if (unlikely(node->p.reverse_hash > reverse_hash)) { - node = NULL; + node = next = NULL; break; } next = rcu_dereference(node->p.next); @@ -828,28 +1355,31 @@ struct cds_lfht_node *cds_lfht_lookup(struct cds_lfht *ht, void *key, size_t key node = clear_flag(next); } assert(!node || !is_dummy(rcu_dereference(node->p.next))); - return node; + iter->node = node; + iter->next = next; } -struct cds_lfht_node *cds_lfht_next(struct cds_lfht *ht, - struct cds_lfht_node *node) +void cds_lfht_next_duplicate(struct cds_lfht *ht, struct cds_lfht_iter *iter) { - struct cds_lfht_node *next; + struct cds_lfht_node *node, *next; unsigned long reverse_hash; void *key; size_t key_len; + node = iter->node; reverse_hash = node->p.reverse_hash; key = node->key; key_len = node->key_len; - next = rcu_dereference(node->p.next); + next = iter->next; node = clear_flag(next); for (;;) { - if (unlikely(!node)) + if (unlikely(is_end(node))) { + node = next = NULL; break; + } if (unlikely(node->p.reverse_hash > reverse_hash)) { - node = NULL; + node = next = NULL; break; } next = rcu_dereference(node->p.next); @@ -861,81 +1391,147 @@ struct cds_lfht_node *cds_lfht_next(struct cds_lfht *ht, node = clear_flag(next); } assert(!node || !is_dummy(rcu_dereference(node->p.next))); - return node; + iter->node = node; + iter->next = next; +} + +void cds_lfht_next(struct cds_lfht *ht, struct cds_lfht_iter *iter) +{ + struct cds_lfht_node *node, *next; + + node = iter->node; + next = iter->next; + node = clear_flag(next); + + for (;;) { + if (unlikely(is_end(node))) { + node = next = NULL; + break; + } + next = rcu_dereference(node->p.next); + if (likely(!is_removed(next)) + && !is_dummy(next)) { + break; + } + node = clear_flag(next); + } + assert(!node || !is_dummy(rcu_dereference(node->p.next))); + iter->node = node; + iter->next = next; +} + +void cds_lfht_first(struct cds_lfht *ht, struct cds_lfht_iter *iter) +{ + struct _cds_lfht_node *lookup; + + /* + * Get next after first dummy node. The first dummy node is the + * first node of the linked list. + */ + lookup = &ht->t.tbl[0]->nodes[0]; + iter->node = (struct cds_lfht_node *) lookup; + cds_lfht_next(ht, iter); } void cds_lfht_add(struct cds_lfht *ht, struct cds_lfht_node *node) { - struct rcu_table *t; - unsigned long hash; + unsigned long hash, size; hash = ht->hash_fct(node->key, node->key_len, ht->hash_seed); node->p.reverse_hash = bit_reverse_ulong((unsigned long) hash); - t = rcu_dereference(ht->t); - (void) _cds_lfht_add(ht, t, node, 0, 0); - ht_count_add(ht, t); + size = rcu_dereference(ht->t.size); + (void) _cds_lfht_add(ht, size, node, ADD_DEFAULT, 0); + ht_count_add(ht, size); } struct cds_lfht_node *cds_lfht_add_unique(struct cds_lfht *ht, - struct cds_lfht_node *node) + struct cds_lfht_node *node) +{ + unsigned long hash, size; + struct cds_lfht_node *ret; + + hash = ht->hash_fct(node->key, node->key_len, ht->hash_seed); + node->p.reverse_hash = bit_reverse_ulong((unsigned long) hash); + + size = rcu_dereference(ht->t.size); + ret = _cds_lfht_add(ht, size, node, ADD_UNIQUE, 0); + if (ret == node) + ht_count_add(ht, size); + return ret; +} + +struct cds_lfht_node *cds_lfht_add_replace(struct cds_lfht *ht, + struct cds_lfht_node *node) { - struct rcu_table *t; - unsigned long hash; + unsigned long hash, size; struct cds_lfht_node *ret; hash = ht->hash_fct(node->key, node->key_len, ht->hash_seed); node->p.reverse_hash = bit_reverse_ulong((unsigned long) hash); - t = rcu_dereference(ht->t); - ret = _cds_lfht_add(ht, t, node, 1, 0); - if (ret != node) - ht_count_add(ht, t); + size = rcu_dereference(ht->t.size); + ret = _cds_lfht_add(ht, size, node, ADD_REPLACE, 0); + if (ret == NULL) + ht_count_add(ht, size); return ret; } -int cds_lfht_remove(struct cds_lfht *ht, struct cds_lfht_node *node) +int cds_lfht_replace(struct cds_lfht *ht, struct cds_lfht_iter *old_iter, + struct cds_lfht_node *new_node) +{ + unsigned long size; + + size = rcu_dereference(ht->t.size); + return _cds_lfht_replace(ht, size, old_iter->node, old_iter->next, + new_node); +} + +int cds_lfht_del(struct cds_lfht *ht, struct cds_lfht_iter *iter) { - struct rcu_table *t; + unsigned long size; int ret; - t = rcu_dereference(ht->t); - ret = _cds_lfht_remove(ht, t, node); + size = rcu_dereference(ht->t.size); + ret = _cds_lfht_del(ht, size, iter->node, 0); if (!ret) - ht_count_remove(ht, t); + ht_count_del(ht, size); return ret; } static int cds_lfht_delete_dummy(struct cds_lfht *ht) { - struct rcu_table *t; struct cds_lfht_node *node; struct _cds_lfht_node *lookup; - unsigned long order, i; + unsigned long order, i, size; - t = ht->t; /* Check that the table is empty */ - lookup = &t->tbl[0][0]; + lookup = &ht->t.tbl[0]->nodes[0]; node = (struct cds_lfht_node *) lookup; do { node = clear_flag(node)->p.next; if (!is_dummy(node)) return -EPERM; assert(!is_removed(node)); - } while (clear_flag(node)); + } while (!is_end(node)); + /* + * size accessed without rcu_dereference because hash table is + * being destroyed. + */ + size = ht->t.size; /* Internal sanity check: all nodes left should be dummy */ - for (order = 0; order < get_count_order_ulong(t->size) + 1; order++) { + for (order = 0; order < get_count_order_ulong(size) + 1; order++) { unsigned long len; len = !order ? 1 : 1UL << (order - 1); for (i = 0; i < len; i++) { dbg_printf("delete order %lu i %lu hash %lu\n", order, i, - bit_reverse_ulong(t->tbl[order][i].reverse_hash)); - assert(is_dummy(t->tbl[order][i].next)); + bit_reverse_ulong(ht->t.tbl[order]->nodes[i].reverse_hash)); + assert(is_dummy(ht->t.tbl[order]->nodes[i].next)); } - free(t->tbl[order]); + poison_free(ht->t.tbl[order]); } return 0; } @@ -944,7 +1540,7 @@ int cds_lfht_delete_dummy(struct cds_lfht *ht) * Should only be called when no more concurrent readers nor writers can * possibly access the table. */ -int cds_lfht_destroy(struct cds_lfht *ht) +int cds_lfht_destroy(struct cds_lfht *ht, pthread_attr_t **attr) { int ret; @@ -955,106 +1551,146 @@ int cds_lfht_destroy(struct cds_lfht *ht) ret = cds_lfht_delete_dummy(ht); if (ret) return ret; - free(ht->t); free_per_cpu_items_count(ht->percpu_count); - free(ht); + if (attr) + *attr = ht->resize_attr; + poison_free(ht); return ret; } void cds_lfht_count_nodes(struct cds_lfht *ht, + long *approx_before, unsigned long *count, - unsigned long *removed) + unsigned long *removed, + long *approx_after) { - struct rcu_table *t; struct cds_lfht_node *node, *next; struct _cds_lfht_node *lookup; unsigned long nr_dummy = 0; + *approx_before = 0; + if (nr_cpus_mask >= 0) { + int i; + + for (i = 0; i < nr_cpus_mask + 1; i++) { + *approx_before += uatomic_read(&ht->percpu_count[i].add); + *approx_before -= uatomic_read(&ht->percpu_count[i].del); + } + } + *count = 0; *removed = 0; - t = rcu_dereference(ht->t); /* Count non-dummy nodes in the table */ - lookup = &t->tbl[0][0]; + lookup = &ht->t.tbl[0]->nodes[0]; node = (struct cds_lfht_node *) lookup; do { next = rcu_dereference(node->p.next); if (is_removed(next)) { - assert(!is_dummy(next)); - (*removed)++; + if (!is_dummy(next)) + (*removed)++; + else + (nr_dummy)++; } else if (!is_dummy(next)) (*count)++; else (nr_dummy)++; node = clear_flag(next); - } while (node); + } while (!is_end(node)); dbg_printf("number of dummy nodes: %lu\n", nr_dummy); + *approx_after = 0; + if (nr_cpus_mask >= 0) { + int i; + + for (i = 0; i < nr_cpus_mask + 1; i++) { + *approx_after += uatomic_read(&ht->percpu_count[i].add); + *approx_after -= uatomic_read(&ht->percpu_count[i].del); + } + } } +/* called with resize mutex held */ static -void cds_lfht_free_table_cb(struct rcu_head *head) +void _do_cds_lfht_grow(struct cds_lfht *ht, + unsigned long old_size, unsigned long new_size) { - struct rcu_table *t = - caa_container_of(head, struct rcu_table, head); - free(t); + unsigned long old_order, new_order; + + old_order = get_count_order_ulong(old_size) + 1; + new_order = get_count_order_ulong(new_size) + 1; + printf("resize from %lu (order %lu) to %lu (order %lu) buckets\n", + old_size, old_order, new_size, new_order); + assert(new_size > old_size); + init_table(ht, old_order, new_order - old_order); } /* called with resize mutex held */ static -void _do_cds_lfht_resize(struct cds_lfht *ht) +void _do_cds_lfht_shrink(struct cds_lfht *ht, + unsigned long old_size, unsigned long new_size) { - unsigned long new_size, old_size, old_order, new_order; - struct rcu_table *new_t, *old_t; + unsigned long old_order, new_order; - old_t = ht->t; - old_size = old_t->size; + new_size = max(new_size, MIN_TABLE_SIZE); old_order = get_count_order_ulong(old_size) + 1; - - new_size = CMM_LOAD_SHARED(old_t->resize_target); - if (old_size == new_size) - return; new_order = get_count_order_ulong(new_size) + 1; printf("resize from %lu (order %lu) to %lu (order %lu) buckets\n", old_size, old_order, new_size, new_order); - new_t = malloc(sizeof(struct cds_lfht) - + (new_order * sizeof(struct _cds_lfht_node *))); - assert(new_size > old_size); - memcpy(&new_t->tbl, &old_t->tbl, - old_order * sizeof(struct _cds_lfht_node *)); - init_table(ht, new_t, old_order, new_order - old_order); - /* Changing table and size atomically wrt lookups */ - rcu_assign_pointer(ht->t, new_t); - ht->cds_lfht_call_rcu(&old_t->head, cds_lfht_free_table_cb); + assert(new_size < old_size); + + /* Remove and unlink all dummy nodes to remove. */ + fini_table(ht, new_order, old_order - new_order); +} + + +/* called with resize mutex held */ +static +void _do_cds_lfht_resize(struct cds_lfht *ht) +{ + unsigned long new_size, old_size; + + /* + * Resize table, re-do if the target size has changed under us. + */ + do { + ht->t.resize_initiated = 1; + old_size = ht->t.size; + new_size = CMM_LOAD_SHARED(ht->t.resize_target); + if (old_size < new_size) + _do_cds_lfht_grow(ht, old_size, new_size); + else if (old_size > new_size) + _do_cds_lfht_shrink(ht, old_size, new_size); + ht->t.resize_initiated = 0; + /* write resize_initiated before read resize_target */ + cmm_smp_mb(); + } while (ht->t.size != CMM_LOAD_SHARED(ht->t.resize_target)); } static -unsigned long resize_target_update(struct rcu_table *t, +unsigned long resize_target_update(struct cds_lfht *ht, unsigned long size, int growth_order) { - return _uatomic_max(&t->resize_target, - t->size << growth_order); + return _uatomic_max(&ht->t.resize_target, + size << growth_order); } -void cds_lfht_resize(struct cds_lfht *ht, int growth) +static +void resize_target_update_count(struct cds_lfht *ht, + unsigned long count) { - struct rcu_table *t = rcu_dereference(ht->t); - unsigned long target_size; - - if (growth < 0) { - /* - * Silently refuse to shrink hash table. (not supported) - */ - dbg_printf("shrinking hash table not supported.\n"); - return; - } + count = max(count, MIN_TABLE_SIZE); + uatomic_set(&ht->t.resize_target, count); +} - target_size = resize_target_update(t, growth); - if (t->size < target_size) { - CMM_STORE_SHARED(t->resize_initiated, 1); - pthread_mutex_lock(&ht->resize_mutex); - _do_cds_lfht_resize(ht); - pthread_mutex_unlock(&ht->resize_mutex); - } +void cds_lfht_resize(struct cds_lfht *ht, unsigned long new_size) +{ + resize_target_update_count(ht, new_size); + CMM_STORE_SHARED(ht->t.resize_initiated, 1); + ht->cds_lfht_rcu_thread_offline(); + pthread_mutex_lock(&ht->resize_mutex); + _do_cds_lfht_resize(ht); + pthread_mutex_unlock(&ht->resize_mutex); + ht->cds_lfht_rcu_thread_online(); } static @@ -1064,27 +1700,56 @@ void do_resize_cb(struct rcu_head *head) caa_container_of(head, struct rcu_resize_work, head); struct cds_lfht *ht = work->ht; + ht->cds_lfht_rcu_thread_offline(); pthread_mutex_lock(&ht->resize_mutex); _do_cds_lfht_resize(ht); pthread_mutex_unlock(&ht->resize_mutex); - free(work); + ht->cds_lfht_rcu_thread_online(); + poison_free(work); cmm_smp_mb(); /* finish resize before decrement */ uatomic_dec(&ht->in_progress_resize); } static -void cds_lfht_resize_lazy(struct cds_lfht *ht, struct rcu_table *t, int growth) +void cds_lfht_resize_lazy(struct cds_lfht *ht, unsigned long size, int growth) { struct rcu_resize_work *work; unsigned long target_size; - target_size = resize_target_update(t, growth); - if (!CMM_LOAD_SHARED(t->resize_initiated) && t->size < target_size) { + target_size = resize_target_update(ht, size, growth); + /* Store resize_target before read resize_initiated */ + cmm_smp_mb(); + if (!CMM_LOAD_SHARED(ht->t.resize_initiated) && size < target_size) { + uatomic_inc(&ht->in_progress_resize); + cmm_smp_mb(); /* increment resize count before calling it */ + work = malloc(sizeof(*work)); + work->ht = ht; + ht->cds_lfht_call_rcu(&work->head, do_resize_cb); + CMM_STORE_SHARED(ht->t.resize_initiated, 1); + } +} + +#if defined(HAVE_SCHED_GETCPU) && defined(HAVE_SYSCONF) + +static +void cds_lfht_resize_lazy_count(struct cds_lfht *ht, unsigned long size, + unsigned long count) +{ + struct rcu_resize_work *work; + + if (!(ht->flags & CDS_LFHT_AUTO_RESIZE)) + return; + resize_target_update_count(ht, count); + /* Store resize_target before read resize_initiated */ + cmm_smp_mb(); + if (!CMM_LOAD_SHARED(ht->t.resize_initiated)) { uatomic_inc(&ht->in_progress_resize); cmm_smp_mb(); /* increment resize count before calling it */ work = malloc(sizeof(*work)); work->ht = ht; ht->cds_lfht_call_rcu(&work->head, do_resize_cb); - CMM_STORE_SHARED(t->resize_initiated, 1); + CMM_STORE_SHARED(ht->t.resize_initiated, 1); } } + +#endif